OK... I'm writing this in my recent experiences...
being able to loop 3dmark on cas2-5-2-2 at 200fsb really pleased me... but that was until I tried running ut2003.
It's weird, but for some reason the bench programs are fine, and pretty much every game runs fine, but ut2003 is very sensitive to minor memory errors, so it's the best way to test for stability.
However, sometimes your memory will not produce an error, especially if it isn't stressedo ut enough..
to ensure that it IS, this is how to test:
1.) start ut2003
2.) settings - set to highest resolution u can use, set all details to highest (i know your game will go choppy, but hey it works)
3.) go to isntant action
4.) choose serpentine deathmatch map, and set bot count to 15 (or more if you enjoy watching slideshows

).
5.) start game... if it doesn't jump out and give an error message within 2 minutes then you have a rock stable system.
This method is EXTREMELY effective. In fact, you dont' even need 2 minutes to test it fully! Even if your memory is just slightly overclocked too much, it will jump out almost instantly.
btw, to all 8RDA+ users... I have noticed something peculiar with my RAM. Many of you also have Winbond memory BH-5 chips like me, so it's worth a try if you are experiencing problems.
Set your ram votlage to 2.77, and set your TRAS to 4. For some odd reason, this is HEAPS more stable, and obviously faster than 5 or above. I have also observed such a peculiarity in my friends system that I built which is using corsair, but same BH-5 chips.
*EDIT: OR YOU CAN JUST NOT READ EVERYTHING I'VE SAID ABOVE, AND RUN 3DMARK03